Methods and apparatus for microelectronic component manufacture

ABSTRACT

Aspects of the invention provide various methods and apparatus for delivering more reliable packaged microelectronic components. One embodiment provides a method in which packaged microelectronic components are heated to a reflow temperature of a selected solder before the solder is applied. After the solder is applied, the performance of the packaged microelectronic component can be tested and any packaged microelectronic component that fails to meet minimum performance criteria can be rejected as defective. Such a process may help identify microelectronic components that may pass normal testing procedures, but fail during a subsequent solder reflow operation. One embodiment provides a system that includes a suitable heating apparatus and a solder plating apparatus, with the heating apparatus being adapted to heat and cool packaged microelectronic components before they are delivered to the solder plating apparatus.

TECHNICAL FIELD

[0001] This invention relates to the manufacture of microelectroniccomponents. More particularly, aspects of the invention provide methodsand apparatus for enhancing quality control in a microelectroniccomponent manufacturing operation.

BACKGROUND

[0002] Microelectronic devices are commonly assembled by couplingtogether two or more microelectronic components. Some of thesemicroelectronic components may comprise single, unpackaged semiconductordies which are electrically coupled to other components of themicroelectronic device, e.g., attaching the die to a printed circuitboard (PCB) or other substrate using wire bonding or flip chiptechniques.

[0003] Increasingly, packaged microelectronic components are being usedto assemble larger microelectronic devices. Packaged microelectroniccomponents typically comprise one or more semiconductor dies, a leadframe that is coupled to the die or dies, and an encapsulant thatcommonly encapsulates the semiconductor die(s) and a portion of the leadframe. One example of such a packaged microelectronic component andsuitable methods of manufacture are disclosed in U.S. Pat. No.5,304,842, the entirety of which is incorporated herein by reference.Other packaged microelectronic components may include small conductivepads instead of a lead frame, with the conductive pads being exposed andpermitting the encapsulated die or dies to be electrically coupled to aPCB or other microelectronic component.

[0004] Such packaged microelectronic components are commonlymass-produced and subsequently assembled into larger microelectronicdevices. One technique for electrically coupling packagedmicroelectronic components to other components of a microelectronicdevice employs a solder applied to the leads or conductive pads of thepackaged microelectronic component prior to assembly with the rest ofthe device. The solder is commonly applied using electrolytic orelectroless plating processes. Each of the solder-bearingmicroelectronic components may then be juxtaposed with a PCB or othermicroelectronic component, with the solder-bearing contacts of thepackaged microelectronic components aligned with corresponding contactson the PCB. The entire microelectronic device (including the packagedmicroelectronic component and the PCB) may then be heated to an elevatedtemperature at which the solder will flow, electrically coupling andphysically connecting the packaged microelectronic component to the PCB.This technique, commonly referred to as a solder reflow process, iswidely used in commercial manufacture of microelectronic devices. Solderreflow processes avoid the need to precisely apply separate balls ofsolder to a number of specific locations on a PCB on a one-by-one basis.This enhances throughput of a microelectronic device manufacturingoperation. The heating required to reflow the solder can cause someother difficulties, though.

[0005] Most packaged microelectronic component manufacturers test eachpackaged microelectronic component before shipping it to a customer.This helps the customer minimize production losses and costs forremanufacturing devices including defective components. Experience hasdemonstrated that some packaged microelectronic components that meet allrelevant performance criteria when the component manufacturer ships themdo not perform properly in the assembled microelectronic device. It isbelieved that many of these “infant mortalities” can be attributed tothe thermal stress placed on the packaged microelectronic componentduring the solder reflow operation. The various elements of the packagedmicroelectronic component often have different coefficients of thermalexpansion (CTEs). For example, the CTE of the encapsulant may bematerially different from the CTE of the semiconductor die or dies, andthe lead frame and associated bonding wires may have CTEs that aredifferent from the CTE of the encapsulant or the die. The relativelyrapid temperature changes of the solder reflow process may inducestresses that cause a previously functional packaged microelectroniccomponent to fail.

[0006] Testing procedures utilized by packaged microelectronic componentmanufacturers often employ an elevated temperature for an extendedperiod of time. Such a “burn-in” process can weed out some componentsthat would otherwise have failed over time during use. However, themaximum temperature of the testing process must be significantly lowerthan the reflow temperature of the solder to avoid damaging the finishof the solder. This can be an even greater problem with advancedmulti-layer solders, e.g., the solder suggested in U.S. Pat. No.5,470,787, the entirety of which is incorporated herein by reference.Typically, burn-in temperatures are less than 150° C., frequently lessthan 125° C. As a consequence, the thermal stresses induced in thesolder reflow process can be significantly higher than thermal stresseswhich can be generated in a burn-in testing process without damagingotherwise acceptable packaged microelectronic components.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a schematic flow diagram of a conventional manufacturingoperation.

[0008]FIG. 2 is a schematic flow diagram of the component packaging stepof FIG. 3.

[0009]FIG. 3 schematically illustrates a microelectronic componentmanufacturing system in accordance with one embodiment.

[0010]FIG. 4 is a schematic side view of a portion of the system of FIG.1 along line 4-4 in FIG. 1.

[0011]FIG. 5 is a schematic cross-sectional view of a portion of thesystem of FIG. 1, taken along line 5-5 FIG. 1.

[0012]FIG. 6 is an exemplary schematic flow diagram in accordance withanother embodiment.

[0013]FIG. 7 is a graph illustrating an exemplary temperature profilesuitable for heating microelectronic components in accordance with onespecific embodiment.

DETAILED DESCRIPTION

[0014] Various embodiments of the present invention provide methods ofmanufacturing microelectronic components and apparatus for use inmanufacturing microelectronic components. The following descriptionprovides specific details of certain embodiments of the inventionillustrated in the drawings to provide a thorough understanding of thoseembodiments. It should be recognized, however, that the presentinvention can be reflected in additional embodiments and the inventionmay be practiced without some of the details in the followingdescription. To facilitate understanding and readability, one exemplarydesign of a microelectronic device manufacturing line is discussed,followed by a description of methods in accordance with otherembodiments of the invention.

[0015] One embodiment of the invention provides a method of processing apackaged microelectronic component. In this method, the packagedmicroelectronic component may be heated to a reflow temperature of aselected solder, which may be on the order of 215° C. or greater. Afterthe heated packaged microelectronic component has cooled to atemperature below the reflow temperature, the selected solder may beapplied to contacts carried by the cooled packaged microelectroniccomponent. Performance of the solder-bearing packaged microelectroniccomponent can be tested and any packaged microelectronic component thatfails to meet minimum performance criteria in the performance testingcan be rejected as defective.

[0016] Another particular embodiment of the invention provides a systemfor processing microelectronic components. The system may include a curestation adapted to receive a first magazine carrying a plurality ofmicroelectronic components, each of which includes a curableencapsulant. The cure station may be adapted to cure the curableencapsulant by heating the microelectronic components to an encapsulantcure temperature in the first magazine. A pre-solder heating apparatusmay be adapted to heat the packaged microelectronic components to areflow temperature of a selected solder. The reflow temperature isgreater than the encapsulant cure temperature. A first transport isadapted to transport the magazine of cured microelectronic componentsfrom the cure station to the pre-solder heating system and transfer thecured microelectronic components out of the first magazine and to thepre-solder heating system. A solder plating apparatus may be adapted toreceive the microelectronic components from the pre-solder heatingsystem. This solder plating apparatus may be adapted to deposit theselected solder on contacts (e.g., leads or conductive pads) or themicroelectronic components. A testing system is adapted to testperformance of the solder-bearing microelectronic components. A secondtransport may be adapted to transfer the microelectronic components fromthe solder plating apparatus to a second magazine and transport thesecond magazine for further processing.

[0017] Conventional Processing

[0018]FIGS. 1 and 2 schematically illustrate various stages in oneconventional process for manufacturing microelectronic devices from asemiconductor wafer. Turning first to FIG. 1, the manufacturing process10 generally includes a packaged microelectronic component manufacturingprocess 12 and a microelectronic device assembly process 14. Thepackaged microelectronic component manufacturing process 12 starts byreceiving a semiconductor wafer from a semiconductor fabricationfacility in step 16. These wafers are typically 200-300 millimeters indiameter and contain a large number of semiconductor dies. The dies aresingulated in step 18. The dies may be singulated in any conventionalfashion, e.g., by attaching the semiconductor wafer to a dicing tape,cutting the wafer with a wafer saw to separate the dies from oneanother, and removing individual dies from the dicing tape.

[0019] These singulated dies may be packaged in a component packagingsubprocess 20. FIG. 2 illustrates the component packaging subprocess 20in more detail. In step 22, the various elements of the desiredmicroelectronic component may be assembled and coupled to one another.By way of example, a semiconductor die may be positioned with respect toa lead frame and contacts on the die may be wire-bonded to the leads ofthe lead frame using conventional wire bonding equipment, such as thatavailable from Kulicke & Soffa. To increase circuit density inmicroelectronic devices, many packaged microelectronic components beingmanufactured today employ two or more semiconductor dies, which may beattached to one another and/or to a lead frame or the like. Once theelements of the microelectronic component are assembled and electricallycoupled together in the desired fashion in step 22, this subassembly maybe encapsulated with an encapsulant in step 24. A wide variety ofencapsulants are commercially available from companies such asThermoset, Lord Chemical Products of Indiana, U.S.A. (e.g., CIRCUITSAFencapsulants) and Dow Corning of Michigan, U.S.A. (e.g., JCR6810encapsulant). The encapsulant is commonly enclosed within a mold and maysubstantially completely surround and enclose the semiconductor die(s).Most conventional encapsulants are thermoplastics that are heat curedfrom a flowable delivery state to a more rigid state.

[0020] If so desired, these encapsulated subassemblies may be mounted ona mounting tape in step 26. In some embodiments, a series of individualsubassemblies may be attached to a continuous mounting tape and the leadframe or other structure may be mounted on the same mounting tapeadjacent. In other embodiments, a series of lead frames my be attachedto one another (e.g., as a strip or matrix of lead frame openings joinedtogether by their respective dams) and each of the dies may be attachedto a paddle or the like of a specific lead from by a separate smallpiece of mounting tape. Whether or not the encapsulated subassembliesare mounted on a mounting tape or the like in step 26, a plurality ofthe encapsulated subassemblies is typically loaded into a magazine fortransport. Such magazines are well known in the art and available in avariety of custom or standard configurations.

[0021] The encapsulant may be cured in step 29. This is commonlyaccomplished by placing the magazine filled with a number of thesubassemblies in a cure chamber. The encapsulant can be heated in thiscure chamber in accordance with the manufacturer's instructions for theparticular encapsulant used. Typical thermal profiles for conventionalencapsulant curing may involve temperatures of 125-175° C. for anextended period of time ranging from a number of hours to 30 minutes orless.

[0022] After the component is packaged in subprocess 20, solder may beapplied to contacts of the packaged component in step 30. This can bedone in a variety of fashions. In one conventional manufacturingprocess, the solder is applied to exposed length of the lead frame usingelectrolytic or electroless deposition techniques. Any suitable soldermay be used. Currently, most solders used in these applications arelead-tin solders, though a number of researchers are attempting todevelop suitable lead-free solders. The solders may be homogeneous, ormay include a more complex structure, e.g., by having an outer layer oftin to serve as an antioxidant.

[0023] Once the solder has been applied, the leads may be trimmed to cutaway the lead frame. The leads may then be formed into a desiredconfiguration, e.g., by being bent at a 90-degree angle to provide anarray of downwardly-oriented leads which can be received in conductiveholes in a printed circuit board or the like.

[0024] The trim and form step 32 yields a finished packagedmicroelectronic component. As noted above, the packaged microelectroniccomponents may be tested to identify components that are likely to failin the field. This may be accomplished using a conventional burn-intesting process, which may involve heating the packaged microelectroniccomponent and applying voltages either statically or dynamically to thepackages. The performance of the circuits in response to the appliedvoltages may be monitored during the burn-in test in step 34. Anypackaged microelectronic components that fail to meet predefined minimumperformance criteria can be identified as defective. The defectivecomponents may be sorted from the rest of the components and the knowngood components can be prepared for shipping to a customer in step 36.

[0025] The packaged microelectronic components produced in themanufacturing process 12 can be shipped to a customer for assembly intoa finished microelectronic device in the microelectronic devicemanufacturing process 14 shown in FIG. 1. This manufacturing process 14may include positioning multiple components on a PCB. While at least oneof the components positioned on the PCB may be a packagedmicroelectronic component produced in the process 12, a variety of otherknown components may also be employed in the same microelectronicdevice. Once the components are positioned on the PCB, this subassemblymay be heated to a reflow temperature of the solder applied in step 30.This reflowed solder may then be allowed to cool, both electricallycoupling and essentially physically welding the packaged microelectroniccomponents to the PCB (step 52). This final assembled microelectronicdevice may be tested in step 54. Any defective devices may be sortedfrom the rest of the devices and the products may be shipped tocustomers in step 56.

[0026] Exemplary Apparatus

[0027] FIGS. 3-5 schematically illustrate a microelectronic componentmanufacturing system 100 in accordance with one embodiment of theinvention. This manufacturing system 100 includes a wafer processingapparatus 110. The wafer processing apparatus 110 may employconventional mechanisms for receiving a semiconductor wafer, mountingthe wafer on a dicing tape, cutting or scribing the wafer, and removingthe singulated dies from the dicing tape. The wafer processing apparatus110 may also include a loading mechanism adapted to load the singulateddies into a conventional die magazine (not shown).

[0028] The die magazine, with a plurality of singulated dies therein,may be delivered to a component packaging system 114 via any suitabletransfer mechanism, schematically shown as transfer 112 in FIG. 3. Forexample, the transfer 112 may include a robot or an automated cartadapted to transfer a die magazine from the wafer processing apparatus110 to the component packaging system 114.

[0029] The component packaging system 114 includes conventionalmechanisms (not shown) for assembling and electrically coupling thevarious elements of the component and molding an encapsulant about thoseelements. These encapsulated subassemblies may be loaded in a magazine120 and positioned in a cure station 116 of the component packagingsystem 114. The cure station 116 is adapted to treat the encapsulatedsubassemblies in the magazine 120 in accordance with the manufacturer'sspecifications for the selected encapsulant material. In one embodiment,the cure station includes an oven cavity which is adapted to maintain anelevated temperature for an extended period of time to heat treat theencapsulated subassemblies at a cure temperature suitable for theselected encapsulant.

[0030] The magazine 120 with the cured microelectronic components may betransported from the component packaging system 114 to a heatingapparatus 130. This transport may be accomplished in any of a variety ofways. In one embodiment, the entire magazine 120 is transferred to theheating apparatus 130 via a suitable transfer mechanism, schematicallyillustrated as transfer 122 in FIG. 3. This transfer may operate in muchthe same manner as the transfer 112 discussed above. A first loadingstation 125 may be positioned adjacent an end of the heating apparatus130. In the illustrated embodiment, the first loading station 125includes a first magazine bay 126 a and a second magazine bay 126 b,each of which is adapted to receive a microelectronic component-filledmagazine 120. A robot 128 or other suitable mechanism may be used toremove the microelectronic components from the magazines 120 in themagazine bays 126 a-b and deliver them sequentially to the heatingapparatus 130. As noted above, the cured microelectronic components maybe mounted on a mounting tape. In one embodiment, a plurality ofmicroelectronic components can be arranged in a strip-like fashion on asingle length of mounting tape and a plurality of these strip-likelengths may be carried in a single magazine 120. In such an embodiment,the robot 128 can remove a single strip of microelectronic componentsfrom the magazine and deliver it to the heating apparatus 130.

[0031] The heating apparatus 130 is detailed in FIGS. 3-5. A bottom wall132, a pair of sidewalls 134 a and 134 b, and a lid 136 may define anoven chamber 150 of the heating apparatus 130. In the illustratedembodiment, the lid 136 is pivotable about a hinge 138 to allow accessto the oven chamber 150. The lid 136 may be provided with a manuallygraspable handle 142 and a peripheral seal 140 can help seal the lid 136against the upper edges of the sidewalls 134 a-b. A component transport152 may be positioned within the oven chamber 150 and extend alongsubstantially the entire length of the oven chamber 150. The transportshould be adapted to support packaged microelectronic components withinthe oven chamber 150 and move the components along the length of theheating apparatus 130. In the illustrated embodiment, the transport 152comprises a conveyor belt that may be supported on a series of rollers(154 in FIG. 4).

[0032] A pressurized air supply 160 may be used to circulate air withinthe oven chamber 150. In the illustrated embodiment, the air supply 160comprises a blower 162 which delivers air to a plenum 164 which mayextend along substantially the entire length of the heating apparatus130. Pressurized air within the plenum 164 can be delivered to the ovenchamber 150 through a series of passages 135 through the sidewall 143 a.In one embodiment, a heat source may be included in the pressurized airsupply 160 to deliver heated air to the oven chamber 150 to heat themicroelectronic components. In such an embodiment, the control of thetemperature profile along the length of the heating apparatus 130 may besubstantially flat.

[0033] In the illustrated embodiment, a series of heating elements 166may be positioned within the oven chamber 150 below the microelectroniccomponents supported on the transport 152. These heating elements 166will heat the air delivered from the air supply 160 after it enters theoven chamber 150. The heating elements 166 may be connected to a powersupply 168. In one embodiment, a series of independently controllablesets of heating elements 166 are spaced along the length of the heatingapparatus 130 and the power supply 168 can be controlled to delivervarying power levels to different sets of heating elements 166,establishing a desired temperature profile along the length of theheating apparatus. In one embodiment, establishing two or threeseparately controllable segments of the oven chamber 150 can provide asuitable temperature profile along the length of the heating apparatus130. A control panel 170 may be used to display operating parameters ofthe heating apparatus 130 and allow an operator to adjust the controlparameters. For example, a plurality of thermocouples (not shown) can bespaced along the length of the oven chamber 150 to measure thetemperature profile of the heating apparatus 130, which may be displayedon the control panel 170. The control panel 170 may be operativelyassociated with the power supply 168 to control the power delivered tothe heating elements 166 to adjust this temperature profile.

[0034] As discussed below, the packaged microelectronic components maybe heated within the heating apparatus 130 to a temperature whichapproaches or exceeds the reflow temperature of the solder which will beapplied to the leads or other electrical contacts of the components. Themicroelectronic components may cool somewhat during pretreatment and/orrinsing stages of the solder plating apparatus 200, described below. Inone advantageous embodiment, however, the microelectronic components areallowed to cool to a temperature below the solder reflow temperaturebefore they are delivered to the plating apparatus 200. If so desired,the microelectronic components simply may be allowed time to cool inambient air before they are delivered to the solder plating apparatus200. In the illustrated embodiment, the heating apparatus 130 includes acooling chamber 180 that is disposed between the oven chamber 150 andthe solder plating apparatus 200. The cooling chamber 180 may take anydesired form. The cooling chamber 180 of FIGS. 3 and 4 includes atransport 182 for moving microelectronic components along the length ofthe cooling chamber 180. The transport 182 may comprise a conveyor beltsupported on a plurality of rollers 184, much like the transport 152 ofthe oven chamber 150. A manually liftable lid 186 may provide access tothe interior of the cooling chamber 180 for maintenance or inspectionpurposes. One or more blowers 188 may blow ambient air through theinterior of the cooling chamber 180, speeding up cooling of themicroelectronic components. In the illustrated embodiment, two separateblowers 188 a and 188 b are positioned on transversely opposite sides ofthe cooling chamber 180.

[0035] In one embodiment, a single, continuous transport mechanism maytransport microelectronic components along the entire length of theheating apparatus 130, i.e., through the oven chamber 150 and thecooling chamber 180. In the alternative embodiment shown in FIGS. 3 and4, two separate transports 152 and 182 are employed and microelectroniccomponents will be transferred from the first transport 152 to thesecond transport 182. In the heating apparatus 130 of FIGS. 3-5, thecooling chamber 180 is spaced from the oven chamber 150, defining atransfer gap 190 therebetween. This gap 190 can facilitate independentthermal control of the oven chamber 150 and the cooling chamber 180. Thetransfer gap 190 is desirably narrower than the width of themicroelectronic components (or a strip thereof) which is transportedthrough the heating apparatus 130. If so desired, a dropped productdetector 192 may be positioned adjacent the transfer gap 190. In oneembodiment, the dropped product detector 192 comprises an opticaltransmitter 192 a and an optical receiver 192 b. Any product which dropsinto the transfer gap 190 will interrupt the beam of light from thetransmitter 192 a to the receiver 192 b, which can trigger an alarm oran automatic shutdown of the transports 152 and 182 to avoid damagingthe products.

[0036] The heated and subsequently cooled microelectronic components maybe delivered directly from the cooling chamber 180 to a suitable solderplating apparatus 200. In one embodiment (not shown), a robot may bepositioned to transfer microelectronic components from the coolingchamber 180 to the plating apparatus 200. In the illustrated embodiment,though, the plating apparatus 200 is positioned proximate the exit ofthe cooling chamber 180. The cooling chamber 180 may be spaced a smalldistance from the plating apparatus 200, defining an exit gap 194. Adropped product detector 196 comprising an optical transmitter 196 a andoptical receiver 196 b may monitor the exit gap 194 much like thedetector 192 monitors the transfer gap 190.

[0037] The solder plating apparatus 200 shown schematically in FIG. 3includes a series of separate processing stations. In particular,microelectronic components may be moved sequentially through apretreatment station 202, a rinse station 204, a plating station 206,and a drying station 208. Such solder plating apparatus 200 are wellknown in the industry and are commercially available from a variety ofsources; a Meco EPL1800 plating system is expected to suffice. Theprecise nature of the operations performed in the pretreatment station202, rinse station 204, plating station 206, and drying station 208 willdepend on the solder being deposited and the specific chemistryutilized. Most commercial solder plating equipment deposits a tin-leadsolder plating on the exposed lead frames of the microelectronicpackages. The solder may be plated on the leads using electroplating orelectroless plating, for example. Nickel-palladium solders can also beapplied in much the same fashion. The process baths employed in thestations 202-208 may be carefully monitored for chemical composition,temperature and the like. If the solder is to be depositedelectrolytically, other operating parameters such as voltage and currentdensity may be precisely controlled in the plating station 206. Theappearance, solderability and reflow temperature, composition, andthickness of the applied solder are key quality control parameters ofthe solder plating apparatus 200.

[0038] In the illustrated embodiment of the manufacturing system 100,the solder is applied in the solder plating apparatus 200 viaelectrolytic or electroless plating. In certain other embodiments, othersolder deposition techniques, e.g., chemical vapor deposition and/orphysical vapor deposition, may instead be employed.

[0039] The solder-bearing microelectronic components may be deliveredfrom the solder plating apparatus 200 to a trim and form apparatus 220.The microelectronic components may be transported from the solderplating apparatus 200 to the trim and form apparatus 220 in any desiredfashion. In the illustrated embodiment, the individual microelectroniccomponents or strips of microelectronic components carried on mountingtape may be loaded into magazines in a second loading station 210. Thissecond loading station may include two magazine bays 212 a and 221 b anda robot 214 to deliver the components or strips of components into themagazines. The magazines may then be transferred (schematicallyillustrated as paths 216) to the trim and form apparatus 220.

[0040] A wide variety of appropriate equipment for the trim and formapparatus 220 is commercially available from a variety of sources.Generally, the individual leads of the leadframe of each microelectroniccomponent may be separated from the leadframe strip, e.g., using a laseror a saw. The separated leads may be placed in appropriate tooling, cutto shape, and mechanically formed into the desired configuration. J-bendand Gull-wing shapes are commonly used for packaged microelectroniccomponents that will be surface-mounted on a PCB or the like.

[0041] Once the packaged microelectronic components have been finalizedin the trim and form apparatus 220, they can be shipped directly tocustomers. In a preferred embodiment, though, these packagedmicroelectronic components are tested before they are shipped tocustomers. In the schematic illustration of FIG. 3, the packagedmicroelectronic components may be transferred along path 222 from thetrim and form apparatus 220 to a test apparatus 230. Any conventionalpackaged microelectronic component testing system can be employed as thetesting apparatus 230. In one embodiment, the test apparatus 230 isadapted to heat the microelectronic components in accordance with apredefined heat treatment regimen. During the heat treatment, voltagecan be applied to the packaged microelectronic components and theirresponse to the voltage may be monitored, e.g., using a suitableprocessor-based system such as a programmed computer 240. Anymicroelectronic component that does not meet certain predefined minimumperformance criteria can be rejected as defective. The defectivemicroelectronic components identified in the burn-in test can beseparated out and only “known good” components will be shipped tocustomers or used in further manufacturing processes, such as themicroelectronic device manufacturing process 14 outlined in FIG. 1 anddiscussed above.

[0042] Exemplary Methods of Manufacture

[0043] Microelectronic components may be manufactured in a variety ofways in accordance with different embodiments of the invention. For easeof understanding, the following discussion of some exemplary embodimentsrefers to the specific manufacturing system 100 shown in FIG. 3. Itshould be recognized, however, that aspects of the present inventioncould be used to manufacture microelectronic components using othersuitable apparatus, as well.

[0044]FIG. 6 schematically illustrates an improved packagedmicroelectronic component manufacturing process 300 in accordance withone embodiment of the invention. This improved process 300 can be usedinstead of the conventional process 12 in the flow diagram of FIG. 1.

[0045] As with the conventional process 12, the packaged microelectroniccomponent manufacturing process 300 of FIG. 6 may start at step 16 withreceipt of a semiconductor wafer from a fabrication process. In step304, individual dies can be singulated from the wafer in the waferprocessing apparatus 110, as explained previously. The singulated diesmay be assembled with other elements and encapsulated in the compositepackaging step 306 using the composite packaging system 114. Thecomposite packaging subprocess 306 of FIG. 6 may be substantially thesame as the subprocess 20 shown in FIG. 2 and detailed above.

[0046] The resulting packaged microelectronic component may then beheated to a suitable elevated temperature in the heating apparatus 130(step 310). The temperature profile of the heating process can becontrolled as desired. In one embodiment, the packaged microelectroniccomponents are heated to the reflow temperature of the solder to beapplied in the solder plating apparatus 200. This solder reflowtemperature will depend on the nature of the solder being used. For astandard eutectic 63/37 tin/lead alloy, the solder reflow temperaturewill typically be at least about 190° C. For most other solders used inconnection with packaged microelectronic components, reflow temperaturesare in excess of 200° C., with lead-free solders typically having higherreflow temperatures than lead-based solders. In one embodiment of theinvention, the packaged microelectronic components are heated in theheating apparatus 130 to a temperature that is as great as or greaterthan the solder reflow temperature. In another embodiment, the maximumtemperature reliably achieved in the heating apparatus 130 may beslightly (e.g., 10-15° C.) less than the anticipated solder reflowtemperature while still achieving many of the desired benefits of theinvention.

[0047] In one particular embodiment, the microelectronic components areheated in the heating apparatus 130 to a temperature of at least about215° C., e.g., about 215-230° C. In another embodiment, the packagedmicroelectronic components are heated to a temperature of at least about220° C. In select embodiments of the invention useful for some lead-freesolders, the packaged microelectronic components are heated to atemperature of about 250° C. or greater. The maximum temperature towhich the components are heated in the heating apparatus 130 can exceedthe maximum temperature to which the components will be heated in asubsequent solder reflow operation, but care should be taken not toexceed acceptable temperature limits of the elements and encapsulant ofthe microelectronic components.

[0048] In one embodiment of the invention, the packaged microelectroniccomponents are heated at a ramp rate which is greater than a ramp rateat which packaged microelectronic components will be heated in asubsequent solder reflow operation. For example, microelectronic devicesmay be heated in a conventional reflow operation from about roomtemperature to about 220° C. over a period of about three minutes. Thisyields a ramp rate (i.e., temperature change divided by time) of alittle over 1° C. per second. As explained previously, this ramp rateand the elevated temperatures achieved in the solder reflow operationmay induce previously acceptable microelectronic components to fail.

[0049]FIG. 7 plots the temperature of a microelectronic component as afunction of time in one exemplary heating process 310. In this process,the microelectronic components are heated from a temperature of about30° C. to about 225° C. over the course of about 38 seconds. This yieldsan overall ramp rate R₁ of about 5° C. per second. Whereas that is theaverage ramp rate from the beginning of the heating process to themaximum temperature, the actual temperature increase need not be linear.In the process of FIG. 7, the temperature is increased from about 70° C.to about 170° C. over the course of about 10 seconds, yielding a maximumramp rate R₂ of about 10° C. per second. In one embodiment, themicroelectronic components are heated in the heating apparatus 130 at anaverage ramp rate during a heating period of at least about 5° C. persecond, e.g., at least about 8° C. per second.

[0050] Once the microelectronic components have been heated to thedesired temperature in the heating apparatus 130, they may be allowed tocool. This can be accomplished passively by allowing the microelectroniccomponents to cool in an ambient environment. In one embodiment, though,the components are actively cooled, e.g., by using a dedicated coolingchamber 180. This will cool off the microelectronic components morerapidly, further thermally stressing the microelectronic components.

[0051] As noted above, in certain embodiments of the invention, packagedmicroelectronic components are removed from magazines 120 and addedsequentially to the heating apparatus 130. The rather large thermal massof the magazines with all of the microelectronic components loadedtherein makes it difficult to ramp up the temperature of themicroelectronic components rapidly. As compared to heating themicroelectronic components individually or in strips, heating the entiremagazine of components both reduces the thermal stress induced in thecomponents and requires additional processing time, reducing throughputof the manufacturing system 100. Solder is typically applied tomicroelectronic components individually or in strips, requiring theindividual components or strips of components to be removed from themagazine. In the manufacturing system 100 shown in FIG. 3, the heatingsystem 130 is placed in line with the solder plating apparatus 200.Since the microelectronic components would have to be separated from themagazine 120 anyway, the microelectronic components can be heated andcooled fairly rapidly in a sequential, single-file arrangement withoutunduly decreasing throughput of the manufacturing system 100.

[0052] One skilled in this technology may expect heating themicroelectronic components at a ramp rate which is significantly higherthan the ramp rate experienced in a subsequent solder reflow operationto cause failure of microelectronic components which would otherwisesurvive the reflow process. Surprisingly, though, it has been found thatthe increased ramp rates (e.g., 5° C./second or more) utilized inembodiments of the invention do not significantly increase productfailures.

[0053] After the packaged components are heated in step 310 and,optionally, cooled in step 312, solder may be applied to the contacts ofthe composite in step 320. As noted above, this may be accomplished inthe solder plating apparatus 200 of FIG. 3. After the solder application320, the solder-bearing packaged microelectronic components may betrimmed and formed (step 322) in the trim and form apparatus 220. Thesetrimmed and formed microelectronic components may then be subjected to astandard burn-in test 324 in the test apparatus 230. Any products thatare identified as defective by the processor-based system 240 can besorted from the rest of the microelectronic components and shipped instep 330.

[0054] It has been found that the improved process 300 can significantlyreduce “infant mortalities” in the field. In particular, a significantmajority of the microelectronic components which pass a conventionalburn-in test but fail during the subsequent solder reflow operation canbe weeded out in the burn-in test 324 of the improved process 300. Thiscan significantly reduce a microelectronic device manufacturer's costsfor product losses or rebuilds.

[0055] Unless the context clearly requires otherwise, throughout thedescription and the claims the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense i.e., in a sense of “including, but notlimited to.” Additionally, the words “herein,” “above,” “below,” andwords of similar import, when used in this application, shall refer tothis application as a whole and not to any particular portions of thisapplication. Use of the term “or,” as used in this application withrespect to a list of two or more items shall be interpreted to coverany, all, or any combination of items in the list.

[0056] From the foregoing, it will be appreciated that specificembodiments of the invention have been described herein for purposes ofillustration, but that various modifications may be made withoutdeviating from the spirit and scope of the invention. Accordingly, theinvention is not limited except as by the appended claims.

I/we claim:
 1. A method of processing a packaged microelectroniccomponent, comprising: heating the packaged microelectronic component toa reflow temperature of a selected solder; after the heated packagedmicroelectronic component has cooled to a temperature below the reflowtemperature applying the selected solder to contacts carried by thecooled packaged microelectronic component; testing performance of thesolder-bearing packaged microelectronic component; and rejecting asdefective any packaged microelectronic component that fails to meetminimum performance criteria in the performance testing.
 2. The methodof claim 1 wherein heating the packaged microelectronic componentcomprises heating the packaged microelectronic component at a rate of atleast about 5° C./second.
 3. The method of claim 1 wherein heating thepackaged microelectronic component comprises heating the packagedmicroelectronic component at a rate of at least about 8° C./second. 4.The method of claim 1 wherein heating the packaged microelectroniccomponent comprises heating the packaged microelectronic component at aramp rate greater than a ramp rate at which the packaged microelectroniccomponent will be heated in a subsequent solder reflow operation.
 5. Themethod of claim 1 wherein heating the packaged microelectronic componentfurther comprises heating the packaged microelectronic component to atemperature greater than the reflow temperature.
 6. The method of claim1 wherein heating the packaged microelectronic component comprisesheating the packaged microelectronic component to a temperature of about215-230° C.
 7. The method of claim 1 wherein heating the packagedmicroelectronic component comprises heating the packaged microelectroniccomponent to a temperature of at least about 220° C.
 8. The method ofclaim 1 wherein the testing comprises heating the microelectroniccomponent to an elevated test temperature that is below the reflowtemperature.
 9. The method of claim 1 wherein the testing is conductedafter the solder is applied to the contacts and the testing comprisesheating the microelectronic component to an elevated test temperaturethat is below the reflow temperature.
 10. The method of claim 1 whereinthe packaged microelectronic component is heated to the reflowtemperature in a heating chamber operatively associated with a solderplating apparatus used to apply the solder.
 11. The method of claim 10wherein the packaged microelectronic component is transferred directlyfrom the heating chamber to the solder plating apparatus.
 12. The methodof claim 1 wherein the packaged microelectronic component is removedfrom a magazine carrying a plurality of other microelectronic componentsbefore heating the packaged microelectronic component to the reflowtemperature.
 13. The method of claim 1 wherein the packagedmicroelectronic component is mounted on a mounting tape, heating thepackaged microelectronic component comprising heating the packagedmicroelectronic component and the tape.
 14. The method of claim 1wherein the packaged microelectronic component is mounted on a mountingtape, heating the packaged microelectronic component comprising heatingthe packaged microelectronic component and the tape, the packagedmicroelectronic component being removed from the mounting tape prior tothe performance testing.
 15. A method of processing packagedmicroelectronic components, comprising: heating a plurality of packagedmicroelectronic components to a stress temperature of at least about215° C.; thereafter, applying a solder to contacts carried by each ofthe packaged microelectronic components; testing performance of thesolder-bearing packaged microelectronic components; and rejecting asdefective any packaged microelectronic component that fails to meetminimum performance criteria in the performance testing.
 16. The methodof claim 15 wherein heating the packaged microelectronic componentscomprises heating the packaged microelectronic components at a rate ofat least about 5° C./second.
 17. The method of claim 15 wherein heatingthe packaged microelectronic components comprises heating the packagedmicroelectronic components at a rate of at least about 8° C./second. 18.The method of claim 15 wherein heating the packaged microelectroniccomponents comprises heating the packaged microelectronic components ata ramp rate greater than a ramp rate at which the packagedmicroelectronic components will be heated in a subsequent solder reflowoperation.
 19. The method of claim 15 wherein heating the packagedmicroelectronic components comprises heating the packagedmicroelectronic components to a temperature of about 215-230° C.
 20. Themethod of claim 15 wherein heating the packaged microelectroniccomponents comprises heating the packaged microelectronic components toa temperature of at least about 220° C.
 21. The method of claim 15wherein the testing comprises heating the microelectronic components toan elevated test temperature that is below 150° C.
 22. The method ofclaim 15 wherein the testing is conducted after the solder is applied tothe contacts and the testing comprises heating the microelectroniccomponents to an elevated test temperature that is below 150° C.
 23. Themethod of claim 15 wherein the packaged microelectronic components areheated in a heating chamber operatively associated with a solder platingapparatus used to apply the solder.
 24. The method of claim 23 whereinthe packaged microelectronic components are transferred directly fromthe heating chamber to the solder plating apparatus.
 25. The method ofclaim 15 wherein the packaged microelectronic components are initiallycarried in a magazine and the packaged microelectronic components areremoved from the magazine before the heating of the packagedmicroelectronic components.
 26. The method of claim 15 wherein at leasttwo of the packaged microelectronic components are mounted on a commonlength of mounting tape, heating the packaged microelectronic componentscomprising heating the packaged microelectronic components and the tape.27. The method of claim 15 wherein at least two of the packagedmicroelectronic components are mounted on a common length of mountingtape, heating the packaged microelectronic components comprising heatingthe packaged microelectronic components and the tape, the packagedmicroelectronic components being removed from the mounting tape prior tothe performance testing.
 28. A system for processing packagedmicroelectronic components, comprising: a first loading station adaptedto receive a first magazine containing a plurality of packagedmicroelectronic components; a heating apparatus adapted to heat thepackaged microelectronic components to a reflow temperature of aselected solder, the first loading station being adapted to transfer thepackaged microelectronic components out of the first magazine and to theheating apparatus; a solder plating apparatus adapted to receive thepackaged microelectronic components from the heating system, the solderplating apparatus being adapted to deposit the selected solder oncontacts of the packaged microelectronic components; and a secondloading station adapted to transfer the packaged microelectroniccomponents from the solder plating apparatus to a second magazine. 29.The system of claim 28 wherein the heating apparatus comprises a heatingzone adapted to heat the packaged microelectronic components at a rateof at least about 5° C./second.
 30. The system of claim 28 wherein theheating apparatus comprises a heating zone adapted to heat the packagedmicroelectronic components at a rate of at least about 8° C./second. 31.The system of claim 28 wherein the heating apparatus comprises a heatingzone maintained at a temperature of at least about 350° C.
 32. Thesystem of claim 28 wherein the heating apparatus comprises a heatingzone and a cooling zone, the cooling zone being disposed between theheating zone and the solder plating apparatus.
 33. The system of claim28 wherein the heating apparatus comprises an oven chamber and atransport system adapted to transport the packaged microelectroniccomponents single-file through the oven chamber.
 34. A system forprocessing microelectronic components, comprising: a cure stationadapted to receive a first magazine carrying plurality ofmicroelectronic components, each of which includes a curableencapsulant, the cure station being adapted to cure the curableencapsulant by heating the microelectronic components to an encapsulantcure temperature in the first magazine a pre-solder heating apparatusadapted to heat the packaged microelectronic components to a reflowtemperature of a selected solder, the reflow temperature being greaterthan the encapsulant cure temperature; a first transport adapted totransport the magazine of cured microelectronic components from the curestation to the pre-solder heating apparatus and transfer the curedmicroelectronic components out of the first magazine and to thepre-solder heating apparatus; a solder plating apparatus adapted toreceive the microelectronic components from the pre-solder heatingapparatus, the solder plating apparatus being adapted to deposit theselected solder on contacts of the microelectronic components; a testingsystem adapted to test performance of the solder-bearing microelectroniccomponents; and a second transport adapted to transfer themicroelectronic components from the solder plating apparatus to a secondmagazine and transport the second magazine for further processing. 35.The system of claim 34 wherein the pre-solder heating apparatuscomprises a heating zone adapted to heat the microelectronic componentsat a rate of at least about 5° C./second.
 36. The system of claim 34wherein the pre-solder heating apparatus comprises a heating zoneadapted to heat the microelectronic components at a rate of at leastabout 8° C./second.
 37. The system of claim 34 wherein the pre-solderheating apparatus comprises a heating zone maintained at a temperatureof at least about 350° C.
 38. The system of claim 34 wherein thepre-solder heating apparatus comprises a heating zone and a coolingzone, the cooling zone being disposed between the heating zone and thesolder plating apparatus.
 39. The system of claim 34 wherein thepre-solder heating apparatus comprises an oven chamber and a transportsystem adapted to transport the microelectronic components single-filethrough the oven chamber.